Frank Lampard, an apparent after-thought when Manchester City added him to their squad in August, ended 24 hours in which he had found himself mired in a dispute between two of his employers by scoring the winning goal in an extraordinary second half here.

The former England international, who completed his move to the Etihad Stadium for the remainder of the season just hours before the end of the old year from MLS club New York City, capped a remarkable sequence that saw five goals in 16 minutes and City – for the second time in four days – give away a two-goal advantage at home.

Pegged back to 2-2, City had energetic attacking left-back Gaël Clichy to thank for his persistence and deft crossing touch as he clipped over a centre which allowed Lampard to capitalise on a slip by Wes Brown, who moved away from his opponent, and steer a superb header into the corner of the Sunderland goal.

It was the fifth league goal of the season for the 36-year-old, who has started just three games under Manuel Pellegrini but has emerged as a vital component of his bid to retain the title, especially with Yaya Touré now poised to leave the club for more than a month for the African Cup of Nations.

Yaya Toure of Manchester City celebrates the opening goal

“I repeat, I don’t think anybody can be surprised by Frank Lampard,” said Pellegrini. “The whole career, the player has [scored] an important amount of goals. I always say he is an important player for us. That’s why we brought him here at the beginning of the season. It’s very important now that he will stay with us until the end of the season.”

There had been no indication of the drama yet to unfold during a turgid first half in which Sunderland expertly followed Gus Poyet’s game plan and packed 10 men into their own penalty area, often for minutes on end, in a successful attempt to frustrate the hosts.

Stevan Jovetic of Manchester City scores his goal

But the first sign of an error was ruthlessly exploited by the defending champions on 57 minutes as Clichy worked the ball in from the left to Stevan Jovetic who, in turn, found Touré who beat former City goalkeeper Costel Pantilimon with a magnificent 22-yard strike, hit with the outside of his right boot. The goal would force Sunderland out of their defensive shell.

Sure enough, nine minutes later, they were again punished after Clichy was allowed space down the left and Jovetic given even more room inside the six-yard area to finish with a superb back heel.

Just four days earlier, City had been in a similar position and allowed a two-goal lead to slip in a 2-2 draw with Burnley but that lesson clearly failed to leave an impression on Pellegrini’s side.

Jack Rodwell of Sunderland heads his goal to make it 2-1

After 68 minutes, another former City player, Jack Rodwell, was left unmarked to steer Seb Larsson’s corner past Willy Caballero in the City goal with a deft header.

And two minutes after that, it was yet another ex-City man, the winger Adam Johnson, who equalised from the penalty spot when Pablo Zabaleta was punished for bringing down Billy Jones following excellent work by substitute Ricardo Alvarez.

An unstoppable left-foot finish from the resulting spot kick placed City under intense pressure although, to their credit, the response was swift and emphatic.

“I think we played a very good game for 90 minutes,” claimed Pellegrini, conveniently forgetting the conceding of two goals in as many minutes. “The only thing we talked to the players about at half-time was not making movements in the final third but then we scored two good goals in 15 minutes.

“After that, it was difficult to understand. Maybe the corner you can because they have very tall players. The penalty, it was too easy for them to come inside our area but once again the team had the personality and character to go for the third goal and we had three or four clear chances to score more.”

Adam Johnson made things all square at the Etihad

Lampard’s winning goal followed three minutes later and the veteran might have claimed a hat-trick before the final whistle, being denied twice by two excellent stops from Costel Pantilimon with powerful shots.

Jesus Navas also found himself clean through, and was denied by the Sunderland keeper, Touré attempted to walk the ball past Pantilimon and into the net, before Fernandinho produced a disappointing attempt from a dangerous position.

But, if nothing else, that closing 20 minutes showed the importance that Lampard has had, and will presumably continue to have, as his current employers – or one of them at least – attempts to beat his old one to the league title.

Frank Lampard heads in the winner for Manchester City just after coming off the bench

It was a point not lost on Sunderland manager Gus Poyet, although he thought City deserved praise, rather than criticism, for the way they had manipulated regulations concerning his signing.

“For me it’s clever, it’s smart. It’s legal, so I’ve got no problem with that,” said Poyet. “But his goal? Yes, I do have a problem with that!

“That’s more something I can control. When you’re playing away at the champions and you find yourself 2-0 down you need to do something very special to come back so after coming back we needed to do better. It’s Frank Lampard, we know what he does. He’s going to arrive late in the box so we need to mark.”